Best Means of Knowing Your Audience?

Pieroxy asks: "As an administrator of various websites, I am always eager to know about my audience. Without going through the hassle of setting up polls and other information gathering systems, the http headers (and connection) are the primary obvious source of information available. However, getting meaningful information out of a User-Agent string or out of an IP address can be trickier than it looks. There are some websites out there that seems to provide some of this information (User-Agent detection, User-Agent explanation, IP localization, or even an IP-to-country mapping), but none seems to be either free, in a usable form or even complete. Would anyone have pointers for free code/service that can help match a User-Agent String with an OS and a browser? A service/code that would match an IP address with a geographic region? Anything else that one can use to try and have a clearer view of its audience?"

Comments

My Idea

[Anonymous Coward]

..is to use PHP to make additions to an XML file, then use a stats.php page to process the info in that XML file and use some of PHP's graphics/graphing functions to visually map it out where I choose to do so.

Or course, I've got to get a better grasp of PHP first...

Anyways, the XML file would be saved as who_yyyymmdd.xml and would be rotated rotated every midnight, server time. I'll probably get a reply or two with "That's a bad use of XML" or "You fail it!", but I'm teh n00b, and it's the best thing I could think of.